Recently several razors have featured shaving heads designed to be dynamically moveable in response to various forces exerted during shaving. An example of such a razor head is the pivoting cartridge sold under the trademark ULTREX by the Schick Safety Razor Group of the Warner-Lambert Company. Such a cartridge pivots about fixed pivot points provided by a handle in response to razor movement during shaving.
A razor head is defined herein and throughout the specification as the combination of a razor blade cap, a razor blade support surface having a guard bar depending outward therefrom and either a single razor blade or a combination of two blades separated by a spacer means with the bottom blade extending farther outward toward the user during shaving than the top blade. The razor head as used herein includes both disposable razors wherein the head and handle are unitary and a cartridge per se used with a permanent handle.
Several patents recently issued to Jacobson, e.g. U.S. Pat. No. 4,446,619 feature individual spring mounting of blades and, additionally, in some instances, a guard bar to provide vertical movement in response to shaving forces. The blades and guard bar are designed to move up and down within the razor cartridge as shaving force is exerted against them. The cap in the Jacobson configurations provide a limiting feature for travel of the uppermost blade in the two blade system and is fixed to the remaining, non-moveable parts of the cartridge. The Jacobson concept, however, does not take into account the configuration of the face which tends to be made up of a flexible series of arcs and angles rather than separate distinct planes.
Other examples of dynamic shaving are found, for example, in U.S. Pat. No. 4,443,939 issued to Vincent C. Motta and Ernest F. Kiraly on Apr. 24, 1984. This razor head configuration discloses a razor cap having corrugated segments disposed on either side of the cap center as well as a guard bar which is individually segmented and a seat portion of the blade support structure from which the guard bar depends having a convoluted, cage-like structure. The spacer in this two blade system has cut out areas to increase flexibility and the blades feature extended longitudinal slots.
The Motta patent describes suspending the cartridge by keyholes provided in the blade support portion and matching key-like projections extending from a handle. The pin means depending downward from the cap of Motta was designed to maintain the individual elements of the razor head in a predetermined configuration. To this end a snap fit configuration for the pin means was provided in which a necked-in portion of the pin means is positioned between an enlarged lower portion and an enlarged upper portion. The lower portion cross sectional diameter is somewhat larger than the receiving holes in the blade support portion. The holes are, however, chamfered to provide sufficient flexibility for the pins to be "snap fit" with the bulbous bottom end passing through the chamfered hole and providing an anchoring site. The tapering necked-in portion allows the blade package comprising the upper blade, spacer and lower blade to ride upward in response to downward forces exerted against the razor head. The upper movement is defined by the length of the necked-in portion.
Another approach for the design of a flexible razor head is found in U.S. Pat. Nos. 4,069,580 issued Jan. 24, 1978, 4,409,735 and resissue U.S. Pat No. 30,913 reissued Apr. 27, 1982 by Syral A. Cartwright et al. This dynamically flexible razor head features a pinless assembly in which the head components are held together either by adhesive strips contacting each of the elements or, in the embodiment depicted at FIG. 7, the blades are inserted into a premolded razor head with slots. The Cartwright embodiment depicted at FIG. 7 shows a fingered cap with the fingers being separated by spaces coinciding with spaces separating ribs of blade support portions for the bottom-most blade in a two-blade system. The blades are inset into mating slots in this particular embodiment. The razor head of Cartwright is also suspended by pins in much the same way as the razor head described in Motta.
Another example of a razor having dynamically moveable elements is described in U.S. Pat. No. 4,516,320 issued to Anthony J. Peleckis in which the razor blade assembly is supported only at each end, and therefore deflects in response to shaving forces while the guard bar moves backward and upward due to certain constructional features.
Each of the razor systems wherein the razor head is moveable suffers from some disadvantage. Both the Cartwright and Motta razor heads, by using cantilevered attachment means are extremely difficult to assemble and the pins utilized for attachment to the handle tend to snap off in response to conventional shaving forces. Moreover, in the case of Motta, flexibility is inhibited because the blade support portion including the guard bar and the cap flex at different flex points. This tends to inhibit the overall flexibility of the razor head.
In the case of FIG. 7 in Cartwright, both cap and blade support portion have open areas which are aligned with each other but the blades are inhibited from free movement by the clamping associated with the slots formed for them in the one piece cap and support structure. The use of relatively thick support ribs also tends to inhibit flexibility.